Here is the circuit diagram of a simple 100 watt inverter using IC CD4047 and MOSFET IRF540. The circuit is simple low cost and can be even assembled on a veroboard.

CD 4047 is a low power CMOS astable/monostable multivibrator IC. Here it is wired as an astable multivibrator producing two pulse trains of 0.01s which are 180 degree out of phase at the pins 10 and 11 of the IC. Pin 10 is connected to the gate of Q1 and pin 11 is connected to the gate of Q2. Resistors R3 and R4 prevents the loading of the IC by the respective MOSFETs. When pin 10 is high Q1 conducts and current flows through the upper half of the transformer primary which accounts for the positive half of the output AC voltage. When pin 11 is high Q2 conducts and current flows through the lower half of the transformer primary in opposite direction and it accounts for the negative half of the output AC voltage.

Circuit diagram.

Notes.

B1 can be a 12V/ 6Ah lead acid battery.

Q1 and Q2 must be fitted to a proper heat sink.

T1 can be a 9-0-9 V primary, 230V secondary, 150VA transformer .

Do not expect much from this circuit. The is very simple one suitable for low grade applications.

I just made the circuit and it worked like a charm. The only problem is, I can lit only upto 5Watt CFL lamp with this inverter. Could you please let me know how I can increase the power of the inverter?
I am using 12-0-12 3Amp Transformer.

dear preeti
R2 is for led protection to limit its current and can be form 1K to 3.3K and if you put higher value the LED lighting
will dim .
diode D@ is for protection of the chip CD4047 from revers polarity of the battery
R1 is for current limit of the CD 4047 and it is better to be 100 ohm 1.5 W
good luck

this circuit isn’t the right because it doesn’t have high power long lasting power when load is connected to it….so i suggest you look for a circuit that has high power efficiency it will be more preferable….please keep me updated soon as you have such circuits….. above you can send me mail via email address…thanks

You are using irf 540 as switching mosfet, of course the center tap will be positive, if you use Transistors 3055 then also it will work or use irf 540 this also work, but irf 540 has higher amp working.

dear mensah
this is a very simple inverter so there is no feedback from output to input to regulate your voltage . about the voltage
drop i can say first your transformer ratio is higher than 12 volt and second your load is higher than the switching
current . use a battery with more current capacity and check your transformer
good luck

hi sir I have few questions I need to ask based on this circuit .
1. without an oscilloscope how do I measure d frequency to 50-60 hz?
2. What would b the output voltage on cd4047 output pins(pin 10 n pin 11)?

hi,
i have made this inverter circuit but i am not getting 230v output from the transformer. can you please tell is the fault?
i am getting 12v at 11 pin but at pin 10 i am not getting sufficient voltage to trigger my mosfet.. so i connected the 100ohm resister to pin 13 where i am getting 12v. so i am getting 12v at the secondary side of the transformer (12-0-12) but not getting output at primary.. i am using a 1.5amp transformer.. please tell me what to do?

Hi Seetharaman!
I liked this circuit since its very simple to implement.
I need to build higher ampere inverter with 36amps, 60hz output. Can I
just change MOSFETs to IRF3205 and transformer rating to 40 amps to increase the load capability. Please suggest.

hello sir iam prepare in 330w inverter 555ic and 4017 ic used and irfz44n also complete the circuit one problem is connect the battery out put voltage is 53 not step up 230v what happen pls tell me sir

hi setharaman ,but if i use 12-0-12v 5amps transformer the output voltage will be perfectly 230v but if i connect a 40w load it will drop to 208v what can i do to maintain just 230-240v,should i use pwm inverter?

hi setharaman when i checked the output of this inverter it showed 295v ac ,but i want to use it for my laptop charge ,for my laptop charger the max input voltage is 100-240 volts only ,is it safe to use this inverter wont it damage the charge by giving over voltage

You can power any device. Ensure you use through surge protected supply sockets as the inverter is a square wave one. ( they call it commercially as computer power supply distribution board with filter and transient suppressor )

Sir,
forgive me if i am making any blunder.
I wish to use this circuit for charging my laptop,mobile etc,will it make problems to laptop adapter (90 w)?
will the primary coil get burned if i run circuit at no load ?
for this will i need a 8A TFR (100w/12v)?

dear abubakar
sending you the formula of winding is not problem but i advise you to order some transformer winding shop to make
for you it is much easy than do it yourself .
refer to fatasheet to compare the transistors
good luck

hi setharaman out of all other different types inverters,i found this is the best,reliable,strong enough inverter but connecting mosfets in parallel to increase output power did not work properly (the output power did not increase),i connected 3 mosfets in parallel ,ie totally i used 6 mosfets with 9-0-9v 5amps transformer ,the output is still 45 watts only

hi can i directly connect this inverter to 30ah car battery,doesn’t the gate region of mosfets or ic(cd4047) will blow due to inrush current.i am asking this question because, i have destroyed many mosfets & ic before by doing so

hi setharaman check this website -www.circuitsgallary.com (simple low power inverter),here they have used 12-0-12v 5a transformer.i tried this circuit with 12-0-12v -5amps & it was a good quality transformer too,but it did not give 60w output

The source drain drop will be approximately 0.6 to 0,8 volts, hence balance voltage of 11.2 to 11.4 will be available across primary winding hence the output voltage will also will be less at 200 volts instead of 230 volts. Check whether each winding is rated for 5a ms that is 12 volt 5 amps and 12 5 amps that is total VA rating is 120VA. not 60 va. In India if they say 12-0-12 @ 5 amps means it is only a 60 VA transformer. with an efficiency of say 60 to 65 % it can produce only 36 to 40 watts output.

hi setharaman what is the necessity of resistor r1,will it decrease the output power ,can i decrease the value. why i am asking this because ,i was testing this circuit with 30ah car battery ,it was working well yesterday but when i started it today it did not work at all & like this many ic’s are damaged .can u give me a solution for this problem

hi i want to use just 7-8 amp transformer because,i saw (in youtube)a guy running his tv,music amplifier,hifi,etc with just 7amp 9-0-9v transformer .he said he used ne555,cd4017& 6 mosfets in parallel ,he powered them all with 7ah battery

How it is possible to get >500VA from a 72 VA transformer. Not practicable. No transformer can have 7 times over load. 25 to 30% over load is possible not greater than that.
To increase the drive current from CD4047 (it is limited to 2mA appox) use NPN transistor like 2N2219 between IC out put pins and the MOSFET. (CD4017 is capable of 6.8mA drive current)

Hi Vasudev your transformer capacity is only 7 to 8 amps, say maximum of 72 VA alone can be expected why 2 MOSFETS in parallel? 1 pair itself can take care up to 150VA. If you want 300VA you can use 2 in parallel (that is 4 MOSFETs) Then your transformer must be rated for 25Amps @ 9-0-9 volts

hi setharam i used a good quality 12-0-12v transformer with 5amp rating instead of 9 volts transformer ,it did not do well at all ,i expected a 60w output & it is not coming ,can you tell me why it is happening. i thing using 9-0-9v at 5 amps is the best idea

hi setharaman i used 9-0-9v transformer with 5a rating, it worked well & gave 40 watts output but that cant do for me .so i wanted up to 200watts of output ,you suggested me to use more mosfets in parallel what should be the value of r3 & r4 . in the link you suggested the values are not properly given

hi setharaman i used 9-0-9v transformer with 5a rating, it worked well & gave 40 watts output but that cant do for me .so i wanted up to 200watts of output ,you suggested me to use more mosfets in parallel what should be the value of r3 & r4 . in the link

No the loss will be quite high and the MOSFETs also may get damaged as the transformer impedance will be quite low. Still it can be used provided you take care of the maximum drive current through the MOSFETs. Make a 500 watts UPS as there are lots of circuit available on the net.

if I could recall, you made a statement about an inverter on which factors it depends on.. (i) the driven maximum current of the transistors and (ii) the transformer maximum current rating. now assume we have in the above circuit the required current rating and we want our inverter to produce more at the output, you said we should include mosfet in parallel?? sorry to ask, the leads how do we get to do that in parallel?? but a question I want to ask, why not in series?? though the question is ridiculous knowing the fact it has three leads… like I said earlier, sorry to ask. I just want to know how and why it has to be the way they are

Please see the reply to Vasudev. Since we have to increase the current drive to the transformer we require more MOSFETs in parallel. Each MOSFET will share the current drive. Say each can drive 10Amps 2 in parallel can drive up to twice the current of one that is 20 AMps. So the energy available at the primary of the transformer is 12 volt X 20 Amps instead of 12 Volt X 10 Amps. The transformer rating should be taken care.

awww! thanks for the above link, btw the circuit for the PWM inverter is awesome too on the site.. and I also found out what wires to use with the image on the site.. please how do we get to upload images of circuits we have practiced here on this site??

The power should not become a common impedance which will lead to instability, (due to power supply lead resistance etc) to avoid we have to decouple the power supply nearer to high current drawing device.

You will get 100VA for little more than 1/2 hr. 500VA UPS also uses this same battery only, it will operate just for 5 minutes, the time for you to save the file on which you are working and to exit, when power fails during operation of PCs.

can i use 220v / 12-0-12 3A center tap transformer … if i use it how much watts and VA i will get plz sir ?? is it mean 12-0-12v 3A = 24v*3a= 72VA or 72*.8= 58watts output ???? how to connect step down 12-0-12 center tap transformer wih this circuit coz i have no step up

Is there any way I can show 12v AC output from this circuit without connecting the transformer? My project supervisor is not allowing me to use transformer at all for safety reasons, so I can’t show him 12V AC. He just wants me to show him inverted 12V ac output. Please help me with this. Tell me what I need to add to this circuit instead of a transformer to show 12V AC output, please explain the procedure. Your help will be gratefully appreciated

Here is the circuit diagram of a simple 100 watt inverter using IC CD4047 and MOSFET IRF540. The circuit is simple low cost and can be even assembled on a veroboard.

CD 4047 is a low power CMOS astable/monostable multivibrator IC. Here it is wired as an astable multivibrator producing two pulse trains of 0.01s which are 180 degree out of phase at the pins 10 and 11 of the IC. Pin 10 is connected to the gate of Q1 and pin 11 is connected to the gate of Q2. Resistors R3 and R4 prevents the loading of the IC by the respective MOSFETs. When pin 10 is high Q1 conducts and current flows through the upper half of the transformer primary which accounts for the positive half of the output AC voltage. When pin 11 is high Q2 conducts and current flows through the lower half of the transformer primary in opposite direction and it accounts for the negative half of the output AC voltage.

Circuit diagram.

Notes.
◾B1 can be a 12V/ 6Ah lead acid battery.
◾Q1 and Q2 must be fitted to a proper heat sink.
◾T1 can be a 9-0-9 V primary, 230V secondary, 150VA

I tried connecting the transformer with inverter and got 230V output. Can you please tell me why the mosfets don’t show any output without connection of transformer? My supervisor for my project asked me to answer this,and I don’t have any clue about it. Please explain in details

Both the MOSFET are alternately switched on use a scope across one of the primary windings. with a multimeter on AC range measure at the transformer secondary for 230 volts. If not check the 4047 circuit fo proper oscillation at 50 Hz check with a frequency meter.

I did not understand the part ‘use a scope across one of the primary windings’ !
I haven’t connected any transformer yet,I wanted to make sure the output from the inverter without transformer is 12V AC first, cause 12v DC from battery should be inverted to 12V ac,but its showing only 0.25!

Hi Jamey you have to use 450V DC or 250 Volts AC capacitor only. Without transformer connected no supply is fed to the MOSFET drains, you will not get any amplification hence no output. You can try with a load resistance also for the MOSFETs, without transformer on an oscilloscope the square waveform will appear.

Seetharaman,Tell me the purpose of C4, what I think it shouldn’t place in parallel on out because it will short the output. In D.C we can use decoupling capacitor but in A.C if u use it in same fashion through capacitor C4 all the voltage will sink to the ground through it & output will become zero.

Hi you are right but here the value is very low and it is used for smoothing the sharp edges of square wave output of the inverter. Such that the square wave edges will get rounded, the harmonic output also will get reduced

How can I make a battery charger circuit and switch circuit for this inverter? How would the all the circuits be connected together? I want that when my main AC power fails,the inverter switches on automatically. Is the relay work for this included in the switch circuit? Please help me out.

hai sir i checked in ur
100w inverter ckt its
working .but i have
one small
problem.when i give
the load to ckt that
time the vge will be
reduced . example i
give 20w cfl to load
that time the o/p
power reduced to
20v . so pls give the
correct solution. my cell number 8088394449 please help me

Sir i done this project. It was working good. but i want to known about the ic 4047 internal constuction how it is giving 180 degrees phase shift pleace it is urgent am doing this my miniproject so i want to give seminar plz sir

I do not practice English fluently so I am forced to use online translation .
I am a modest French electronics and retired for 4 years , I have invested in renewable energy for personal use (2.5 KW Photovoltaic and wind)
Everything works fine . But less than 4 years , 2 3 KW inverters sine did not take the road as unreliable.
I decided not to buy expensive and impossible to repair converters. So for almost a year , I’m looking for a solution to build a converter 3 KW .
Currently , I experimented with a 555 + SA 4017 CD . Power mosfets IRFP 250/ 260 IRFP . The transformer is a 3 KVA new. Several mosfets are connected in parallel when the development will be effective .
The result is insignificant. Look here:
http://libre-infos.eklablog.com/electronique-c19781471

Do you think the use of CD 4047 will improve the power expected .
What is the width of the pulses delivered by the 4047 CD , compared with the 4017 CD ?
Watch here the draft very temporary mounting with a 120 W lamp that lights the secondary half . 120 volts measured with a digital controller.
If you wish, thank you to tell me what you think.

What is the function of that POT?.and is the transformer a normal one or do i hv to use a center tapped one?…i’m asking this cuz i’m having 3 wires in my transformer n i knw one handles 110V..wont it smoke up the shit?!

hai sir i checked in ur
100w inverter ckt its
working .but i have
one small
problem.when i give
the load to ckt that
time the vge will be
reduced . example i
give 20w cfl to load
that time the o/p
power reduced to
180v . so pls give the
correct solution.

Hi Manikanth if you increase the AH of the battery the inverter will work for a longer duration. say if you use a 12 volt 7AH battery for this inverter you will get the inverter going for 45 minutes if your load is 100VA. if you use a fully charged 12 volt 40AH battery it will work for 4 1/2 hours without needing for recharge for the same load.

hai sir i checked in ur 100w inverter ckt its working .but i have one small problem.when i give the load to ckt that time the vge will be reduced . example i give 20w cfl to load that time the o/p power reduced to 180v . so pls give the correct solution.

555 timer has only one output. But 4047 has two outputs which are compliment to each other. Similar to a flip-flop. Moreover, conversions like this – DC to AC, AC to DC etc has more power loss. 4047 is a CMOS IC and hence consumes very low power compared to the TTL 555 timer. Any way the obvious reason may be the two kinds of o/p offered by 4047 and also, it uses minimal external components than 555.

hi, you can use normal transformer which in E,I core.transformer always works on ac voltage.you can use 9-0-9 ac transformer with 10 amp.if your monitor wattage is less than 100 w than you can use this circuit.transformer can work both sides if you give input 220 v ac than it become step down 9-0-9 ac and if you give this side 9-0-9 ac then it can give us 220v ac and called step up transformer.so same transformer can work both things.

hello, i am new to electronics ,this circuit inspired me a lot, so i wanted to try it, but the capacitor c4 of 0.1uf/600volts is not available for me…so tell me any alternate..and by connecting the capacitors in parallel the capacitance can be added no,so can i try in that way……?m plz give ma a solution for that…….!

hi chandrasekar!! you asked a question about the charging prob. right the same question too rised for me!! i have post the comment, no reply for that!! did you got the answer from or you got help from others? if so pls reply for me!!!

Hi sir.. actualy i m getting the output as 82v at secondary of the transformer.I checked all the pins then i came to know that voltage is getting droped at 4th pin there by m not getting voltage at 11th pin so the second mosfet is nt conductng completely where m gettng only 4.35v at primary of transformer connected to drain and center tap where in for first mosfet m gettng 9v.. so what would be the mistake..??

Hi Nithin the transformer should be rated for 9-0-9 volt at 150VA. Use standard polyester or ceramic disc capacitor rated for 25 to 100volt 103 for C2 and 104 / 600 volt polyester for C4. What you have indicated some imported non standard capacitors their values will not be as you expect. Kindly nuse standard CTR / philips etc

HI Nithin you can use 1N4001, Preset to fix the inverter frequency at 50 or 60Hz, With the rcommended battery 30 minutes approximately.
Hi Avinash you can get the current flow with respect to one wire in the other, hence both the wires are required. if you say that line tester is glowing on both wires(it will sinece the secondary of the transformer is floating) if you want to avoid this, you ground one wire of the secondary.

Hi Sunil use 250volt tap, if available in the transformer. Hope the transformer used is 96VA rating. If taps are not available you can use a 230V/24volt 24VA transformer and step-up the voltage.(Like a step voltage regulator)

I am totally new to electronic but I have always been looking to make my own inverter circuit. Its just for fun or for my understanding purpose, I wonder if someone out here can guide me or share me their circuits. Basically, I’m not looking to generate lots of energy from 12v battery, I need a circuit which invert 1.5v/3v to some higher range.

Hi Kirthik your transformer should be low loss type. If you want 45 watts out put say at PF 0.8 then the VA at secondary should be 56VA and if the transformer efficiency is say 80% then the primary side requirement is around 70VA with 12 volt supply the requirement is 6 amps approximately. Your transformer should be for a primary of 10.8-0-10.8Volt and with a rating of 70 VA. Secondary should be rated for 230 volts. (a torroidal transformer will be a better choice)

I did the same circuit with the 2n3055 power transistor instead of IRF540 and i have used 12-0-12 ,3A transformer , so in this case , maximum how much Watts(W)i can able to consume from the transformer , that too even if i setted the frequency to 50 Hz at that time trafo output was 233V but after connecting the 15W CFl voltage came to 96 V, but if i am increasing the frequency to 300Hz then the voltage was around 172V AC ,i want to take min of 45 Watts output so what should be the rating of transformer???

SIR,
I’M BEGINNER IN ELECTRONICS WITH SOME ELECTRICAL KNOWLEDGE IN MAINTENANCE OF HIGH VOLTAGE MACHINES.WHEN I INTENDED TO BUILD AN INVERTER FOR 3*25W CFL LAMPS I FOUND YOUR CIRCUIT.I’VE DOUBT ABOUT CHARGING OF THE BATTERY.IS IT NEEDED EXTRA CIRCUIT?IS THE VOLTAGE GETTING LOW IF CHARGE OF THE BATTERY GETTING REDUCED? PL. REPLY IMMEDIATELY
THANKS
SANTHOSH

My Another Question, This is not related in this circuit , But i want your help., My Numaric 600 VA UPS in problem., MOSFET 85T03GP Not available.,
Any other substitute for this mosfet?
Pls give the Number pls thank you., sir

sir.. today i have done this expt. with all u said equipments… its cost i payed 200rs…. so i made connections when i given 12v dc supply to it then the capacitor which is placed near power supply (c3 2200/25v) it got burned… can u tell me why this happened….?? connections was accurate… sir plz reply soon…

Hi Ali the battery capacity is given by 12 X 7AH that is 84VAH. say you draw 30 watts with 0.8PF and 85% inverter efficiency. The VA requirement will be 44VA. dividing the capacity with this value you will get the maximum operation duration of new fully charged battery. 84VAH / 44VA = 1.909H, that is 1hr and 55minutes.

Hi Haidar the harmonics are taken care by the output filter capacitor C4 you can increase it to 0.47uF 630V AC. This is sufficient to take care of all harmonics hence can be used with computer, Solid state TV etc (sensitive electronic gadgets)

Hi Haidar all resistances can e 1/4 watt. You can use 9-0-9 75 VA transformer you will get higher voltage with low loads and at rated load it will be alright. 11-0-11 120VA is the transformer which suits better.
Hi Azrin you can use 12-0-12 but output voltage will be around 200volts with 230V secondary winding and with 250V winding the output will be 220volts.

Hi Nihar with a MOSFET transistor as their switch on resistance are quite low you can can use 12-0-12 transformer the right choice. dont use 9-0-9 transformer with MOSFET. use recommended transistors for 9-0-9 transformer use.

i have a 9-0-9 transformer from an old u.p.s .when i connect the transformer to the mosfet ,the mosfet becomes hot at no load condition ,output is 280 volt,when battery voltage decreases it works properly.i changed the transformer to 12-0-12 ,mosfets are not heating, the output is 220 volt .this is suitable.please tell me how can i use the 9-0-9 transformer safely . thanks in advance..

hi, i have made this circuit at the pcb board(holed).
the current is passing through IC but there isnt any output at secondry winding of transformer . even that ihave checked the ckt. thrice and there isnt any mistake in connections . none of the joints is loose and each of them have been soldered. also please let me know an alternate transformer (with its current and voltage ratings) that can be used in same citcuit without alterations.please respond soon .also please send me its block diagram, would be really helpfull.

Hi Neo the battery voltage is switched on alternately to the primary of the transformer. The switching device is MOSFET the drop across them is negligible hence full battery voltage will be available across primary winding. if the transformer is 9 volt with 9 volt output will be 230volt square wave if it is 12 volt you will have 33% higher voltage at the output. without load you will get around 300 volt square wave.

Hi, I don’t know much about power electronics. I build this circuit with 9-0-9 v primary and 230 v secondary (115-0-115)transformer.
I get output 240 v at secondary when I connect center tap of primary to 11 v and much higher when connected to 12 v. what is this relationship, is there a formula that I can use to work out what voltage center tap should be connected for this type of transformer.
Thxs

Hi Sankalp CD4047 is a CMOS IC iy can give an output of around 1mA which is not sufficient to drive the transformer directly, hence you require transistor take care of the high current drive to the transformer. The MOSFETs used are enhancement type they require bias to conduct. These devices require voltage drive ( around 2.5 to 4 volt)with very little current. cmos IC can take care of this.

Hi Seetharaman,tnx for ur quick responsed,i appreciate it so much,for this i gained more info on how your circuits work!!tnx for the additonal websites,,now i am searching parts,first for the transformer for this project.tnx GODBLESS.

Hi Darren you have to take saturation voltage of the final power transistor at 5 amps say it is 2 volt you require a 12 – 2 = 10 volt transformer (10-0-10). if you use 12 volt you will get 10 to 15% less out put voltage, if that is ok you can go ahead..

Hi Shashi One ceiling fan say 48″ it will consume 90watts, two CFL 18 watts so total requirement is 108watts say inverter efficiency is 85%. Then the primary requirement is 108 / 0.8 = 135VA if the battery voltage is 12 then the current requirement will be 11.25Amp. your battery capacity is 7AH so if draw 7amps it will supply for 1hr approx so if you draw 11.25 amps the battery can supply for 35 minutes. hence your back up will be for appoximately 35minutes